I'm trying to use xargs to run a command for each provided argument, but unfortunately the --replace/-I flag doesn't seem to work properly when conjugated with -n.
It seems that {} will expand into the full list of arguments read from stdin, regardless of the -n option.

Unfortunately all of the examples on the web seem to be for commands (mv, cp, rm) which will take multiple arguments where {} is expanded.

For example, when running:

echo a b c d | xargs -n 1 -I {} echo derp {}

The output is:

derp a b c d

But I expected:

derp a
derp b
derp c
derp d

However, running it without -I {} yields the expected result:

echo a b c d | xargs -n 1 echo derp
derp a
derp b
derp c
derp d

Is there any way to achieve this with xargs?
My ultimate intention is to use it to run multiple (parralel) ssh sessions, like